It is known that windshield wiper blades made of an elastomer, for instance, of vulcanised rubber, must be subjected to a surface treatment before they can be used because they have, in the absence of such treatment, an unduly high surface tackiness, a low self adherence and low abrasive resistance. There exists a certain number of physical treatment processes such a facing with solid lubricants or coating by means of suitable polymers. These processes do, however, have a certain number of drawbacks and there is, therefore, a tendency to use chemical processes based on halogens or halides such as fluorine, the fluorides, chlorine or bromine.
This chemical treatment is traditionally effected in the aqueous phase which has the drawback of limited efficiency. One may, obviously, consider a treatment in the gaseous phase in the general case where the windshield wiper blades are manufactured by moulding, for instance, in platen presses, for it is fairly easy to introduce the moulded element into a closed vessel containing a gaseous treatment atmosphere.
The applicant has, however, perfected a continuous manufacturing process for windshield wiper blades wherein there is effected a continuous extrusion of a strip whose cross section has the shape of two wiper blade sections which are interconnected by their lip zones; these zones constitute the central portion of the strip intended to be cut into two in the longitudinal direction to form two identical sections from which there will be cut out the individual lengths forming the wiper blades. The usual batchwise chemical treatment processes, especially by means of the halogens, may therefore no longer be entertained from an industrial point of view, with the means which are currently known.
If it is desired to effect a treatment of an extruded polymeric section by means of a halogen in its gaseous phase and if it is desired that this treatment should be effected on a continuous basis at the rate of production of the extruded section, one is faced with a difficult problem since the vessel wherein this treatment is to take place is necessarily open at the two ends to allow the extruded section to pass, and in this case there occur leaks of the gaseous halogen used for the treatment into the outer atmosphere. Now, it is known that the halogen gases are extremely dangerous for the personnel and the surrounding equipment so that an apparatus of this type entails the absolute obligation of taking considerable safety measures and necessitates the commissioning of costly protection equipment.
The object of the invention is to provide a reactor operating on a continuous basis and allowing the fixation of the treatment gas on a solid to be treated, without the treatment gas being able to escape outside the reactor. In the case of the making of a windshield wiper blade of a rubber polymer, the treatment gas is advantageously chlorine and the reactor according to the invention makes it possible to ensure fixation of the chlorine on the rubber, without any emanation of chlorine outside the reactor. From French Pat. No. 1 092 664, there is known a reactor for ozone treatment of polyethylene films, but in this known apparatus the treatment gas does escape outside the reactor.